By virtue of their electrical properties, tubes generate a special waveform when they're saturated, which is why tube engineering has tremendous tonal advantages over solid state or DSP solutions, particularly for crunch and lead sounds. Tubes enter the saturation zone gradually or softly, which lends tube-driven tone its trademark yet totally unique character.
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By practising slow and speeding up over time(also by using a metronome). Also by palm muting with your picking hand to stop the wrong strings from sounding. You can also mute the strings with your left hand as well. Main thing is to keep playing them slow and dont play the arpegios faster than you can handle them !